TL;DR
The batteries inside brain implants could soon pack more energy into the same tiny space. EVE Energy, a Chinese battery maker, has rolled out a coin-sized battery with no liquid inside, built mainly for implants that connect the brain to computers, and says it holds 40% more energy for its size than ordinary cells of the same kind. If that holds up, devices that help people with paralysis or lost speech could run longer between charges or replacements, or shrink. It is the same solid-state chemistry the big battery makers are racing to put in cars, arriving first at the smallest scale. For now the figures are the company's own and untested, and no one has said when the cell will be made in volume.
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